Boolean expressions

The AND operator is always implied between terms, that is: web error is the same as web AND error. So unless you want to include it for clarity reasons, you should not need to specify the AND operator.

The NOT operator only applies to the term immediately following NOT. To apply to multiple terms, you must enclose the terms in parenthesis.

Inclusion is generally better than exclusion. Searching for "access denied" will yield faster results than NOT "access granted".

Order of evaluation

The order in which the Splunk software evaluates Boolean expressions depends on whether you are using the expression with the search command or the where command. This includes the implied search command at the beginning of the search.

The following table describes the order in which the Boolean expressions are evaluated.

Order

Search command

Where command

1

Expressions within parentheses

Expressions within parentheses

2

NOT clauses

NOT clauses

3

OR clauses

AND clauses

4

AND clauses

OR clauses

Examples

The following examples show how Splunk software processes Boolean expressions.

Consider the following search:

A=1 AND B=2 OR C=3

This is the same as specifying A=1 B=2 OR C=3

When you specify values without parenthesis, this search is processed as:

A=1 AND ( B=2 OR C=3 )

Here is another example:

error NOT 403 OR 404

Without parenthesis, this search is processed as:

Search for any event that contains the string "error" and does not contain the keyword 403

Comments

I think "error NOT 403 OR 404" is not the same as "error NOT = 403 OR error = 404". At least the latter seems to imply that the field "error" does not contain the value "403" respective does contain the value "404".
I thought "error", "403" and "404" are just strings that are included or not in the raw data.

Boolean expressions

Enter your email address, and someone from the documentation team will respond to you:

Send me a copy of this feedback

Please provide your comments here. Ask a question or make a suggestion.

Feedback submitted, thanks!

You must be logged into splunk.com in order to post comments.
Log in now.

Please try to keep this discussion focused on the content covered in this documentation topic.
If you have a more general question about Splunk functionality or are experiencing a difficulty with Splunk,
consider posting a question to Splunkbase Answers.

0
out of 1000 Characters

Your Comment Has Been Posted Above

We use our own and third-party cookies to provide you with a great online experience. We also use these cookies to improve our products and services, support our marketing campaigns, and advertise to you on our website and other websites. Some cookies may continue to collect information after you have left our website.
Learn more (including how to update your settings) here »